fix: jumplist picker indexing the line after

[Hippo0o]

Description

jumplist entry text is currently 1 line after

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

local lnum = 3
print(vim.api.nvim_buf_get_lines(0, lnum, lnum + 1, false)[1])
-- this will give the text of line 4
print(vim.api.nvim_buf_get_lines(0, lnum - 1, lnum, false)[1])
-- this will give the text of line 3

Configuration:

• Neovim version (nvim --version): v0.8.1
• Operating system and version: Arch

Checklist:

• My code follows the style guidelines of this project (stylua)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (lua annotations)

[Conni2461]

Thanks :)